Substances such as metal or edible materials are easily oxidized when exposing to the air. Such substances are generally preserve in sealed boxes. However, they are still easily ruined or staled by the air inside the sealed boxes.
In addition, it is difficult to notice tiny oxidized portions in delicate substances such as tea leaves or coffee grounds. Therefore, a need remains for a vacuum sealed container to provide an improved preservative and examinable environment for easily oxidized substances.